A crystal is any solid that has an organized structure. ... So it is a prerequisite to be a crystal in order to be a mineral. All minerals, therefore, form crystals. On the other hand, there are crystals that are not minerals, because they are not naturally occuring, or because they are not inorganic
Source: http://www.geologyin.com/2016/03/what-is-difference-between-minerals-and.html?m=1
